Carbon fiber reinforced composite materials are widely used in recent devices, such as aviation instruments and electronic devices. The carbon fiber reinforced composite materials have high thermal conductivity, anisotropy, or high specific rigidity. In the carbon fiber reinforced composite materials, the anisotropy generated by orientation of carbon fibers causes a large difference in mechanical properties (e.g. strength and rigidity) and thermal properties (e.g. thermal diffusivity and thermal conductivity), so that evaluation (measurement) of the anisotropy is important.
Examples of known fiber orientation evaluation methods include X-ray computed tomography (XCT) test and tensile test.
For example, patent document 1 discloses analyzing a tendency of an orientation state of a filler in a part of a resin molded product using a power spectrum image. The power spectrum image is obtained by binarizing a slice image of the resin molded product obtained by the XCT test and Fourier transforming the binarized image.